Citi★3.9 (21k)· London

Work with Solidity, Web3J/Web3JS/Ethers.js/Viem, Java/Spring, Node.js, and blockchains such as Ethereum, Hyperledger Besu, Canton, and Solana, using Hardhat/Foundry/Truffle for testing. Contribute to Citi's Integrated Digital Assets Platform (CIDAP) building Web3 components for tokenization, smart contracts, and on-chain settlement.

Samsara★3.6 (32)· London

Samsara interns work on the Connected Operations Cloud, building backend infrastructure in Golang, web clients with TypeScript/React and GraphQL, mobile with React Native, or embedded software for IoT devices. Projects involve scaling data ingestion, real-time data processing, and creating actionable insights for industries like transportation and agriculture.

Backend engineers use Python, Django, Django-REST-framework, GraphQL (Graphene), Celery, Postgres, and AWS (Packer, Consul, Terraform). They build and maintain the AI-driven energy management platform that powers utilities and optimises renewable generation. The global engineering team is around 1,400 people.

Python micro-services with RabbitMQ and OpenShift/Kubernetes, using SQL Server and Parquet. The London Commodities Risk Technology team builds a front-office distributed platform for trading and risk calculations on assets like oil, gas, power, and exotics, collaborating with traders and quants.

Work with C# on .Net Framework 4.5.2+ and .Net 5+, using NUnit, xUnit, REST, Kafka/RabbitMQ, Git, and Linux. You will build Citi’s next-generation Equities technology platform for execution, clearing, and margin processes.

Reward Gateway★4.4 (11)· London

Define and champion the architecture vision for the Engagement Business Unit, working with global architecture and engineering leaders. The role involves leading architecture governance, establishing reusable patterns, and driving the adoption of AI-enabled engineering practices across APIs, microservices, event-driven systems, and data streaming platforms like Kafka. You'll partner with product and engineering teams to deliver scalable cloud-native applications and improve CI/CD pipelines and software delivery practices.

Koinly★3.0 (1)· London

Work with React 19, TypeScript, TanStack (Router, Query, Table), Radix UI, Mantine, Tailwind CSS v4, Vite, Vitest, Storybook, Highcharts, Sentry, Bun, and RabbitMQ on a data platform that reconciles crypto transactions and tax obligations for Koinly’s web application, with a React Native mobile app joining scope later.

Koinly★3.0 (1)· London

You will work with TypeScript on Bun, RabbitMQ, Redis, PostgreSQL, Vitest, Sentry, and Rust. The team owns the distributed data-processing backend that ingests, normalizes, and reconciles on-chain and exchange data for Koinly’s crypto tax calculation product.

Senior WordPress Developer role: build bespoke WordPress sites and apps using PHP, MySQL, ACF, WooCommerce, Gutenberg, JavaScript (ES6+), SASS/SCSS, Git, Composer, npm, Vite, CI/CD. You’ll also drive AI-assisted development (RAG, MCP, Copilot) and mentor junior developers.

Spotify★4.1 (116)· London

You will work with React, TypeScript, Java, GraphQL, PostgreSQL, and Google Kubernetes Engine (GKE) to build end-to-end solutions. The team builds Groove, a platform that helps thousands of employees plan, coordinate, and deliver work across Spotify.

Design, configure, and develop HR web applications using React, Next.js, and the HRSD platform. Build reusable UI components, integrate with REST/GraphQL APIs, and participate in CI/CD processes alongside product managers, designers, and backend engineers.

You will work with Java, Spring Boot (Spring Batch, Spring Cloud), microservices, REST APIs, GraphQL, Azure Cosmos DB, and Confluent Kafka. The team builds AI-driven digital products and services that support employees and HR stakeholders.

Working with Python, SQL, AWS, and APIs like GraphQL, gRPC, and REST, you will productise ML models and manage data workflows in cloud infrastructure. The HealthTech team focuses on ethical AI to improve patient care outcomes.

Nuffield Health★3.2 (939)· London

You will work with Java 21, Spring Boot, Maven, RabbitMQ, Apache Camel, Git, GitHub Actions, Docker, Azure DevOps, Terraform, Ansible, and SQL databases. The Integration Squad designs, develops, and supports microservices and APIs for Nuffield Health's digital healthcare platforms, enabling secure connectivity across internal and third-party systems.

MAREX★3.2 (6)· London

You will work with C# .NET, JavaScript, TypeScript, React, Node.js, GraphQL, Docker, NoSQL/RDMS databases, and AWS cloud services (ECS/EKS, Lambda, S3, RDS, API Gateway). The team builds and maintains applications to strengthen the company’s market-making capabilities and improve operational efficiency across multiple asset classes and geographies.

A full-stack or backend specialist will use C# and .NET Framework, SQL Server (T-SQL), RESTful APIs, Azure DevOps, and messaging queues (RabbitMQ, Kafka) to build secure integration pipelines and backend services. They will execute a critical integration programme for an international Wealth Management firm to connect core internal and third-party systems.

As a Backend Software Engineer, you'll use Go or Node.js to build and scale the company's core real-time messaging platform, working on low-latency Pub/Sub services and state synchronization in an AI-first engineering environment.

You will work with React, TypeScript, Next.js, Jest, Cypress, CSS-in-JS libraries, Git, and GraphQL. You will join the Customer Apps team to build and scale customer-facing applications for payment device management, loyalty schemes, and more at Dojo, the UK's largest payments acquirer.

Tripadvisor★3.9 (142)· London

Android Engineer role working with Kotlin, Coroutines, Jetpack Compose, Cursor, and GraphQL in a modular, clean-architecture MVVM layout. You will build and release code for the Tripadvisor Experiences mobile app, collaborating with product and designers on the full software lifecycle. This is a full-stack role where you primarily develop Android systems, with occasional back-end projects.

Tripadvisor★3.9 (142)· London

You will work with Kotlin, Coroutines, Jetpack Compose, Cursor, GraphQL, and MVVM in a clean-architecture modular layout. You’ll join the Tripadvisor Experiences mobile team, focusing on Android app development with occasional backend microservices work.

Python (3.10+) and Go development, with JavaScript/TypeScript for frontend; using RabbitMQ, Kafka, PostgreSQL, Redis, OpenTelemetry, and Prometheus. You will build and maintain low-latency real-time data feeds and web scraping pipelines to expand access to liquidity providers for sports prediction models.

Senior Software Engineer designs and maintains backend services and APIs using Java, Python, and Node.js, working with microservices and Spring Boot. The role involves building REST, GraphQL, and SOAP APIs, using relational and NoSQL databases (MySQL, PostgreSQL, Oracle, Redis), and performing cloud-native development in AWS environments. This position supports financial systems and integrations within the leading global business aviation company, Vista.

Build and support scalable enterprise integrations using Workato, APIs, webhooks, REST, SOAP, GraphQL, OAuth, JSON, XML, SQL, JavaScript, Python, and Workato formulas. Integrations span finance, HR, CRM, document management, and analytics platforms. No team size specified.

Senior Full Stack Engineer working with TypeScript, React/Next.js, GraphQL and modern cloud infrastructure on an AI-powered platform that automates data collection, reporting and collaboration for investment firms. You join a small engineering team and collaborate directly with founders.

Work with TypeScript, LangChain, React, GraphQL, Prisma, Temporal, and LlamaIndex to build AI agents that automate high-stakes banking workflows. You will own features end-to-end, architecting a core platform that orchestrates AI, customers, and humans to replace legacy banking bottlenecks.